We are continuing our studies on the biological role of polyamines. Particular attention is being directed towards the selection of Escherichia coli and yeast mutants that are defective in the biosynthesis of these amines, and a study of the resultant phenotypic effects. We are also studying the control of polyamine biosynthesis in the yeast mutants. Studies are also being carried out on the characterization of the specific enzymes involved in spermidine biosynthesis, with particular emphasis on adenosylmethionine decarboxylase from prokaryote and eukaryote sources. We are also identifying plasmids carrying the specific E. coli genes and preparing plasmids carrying the yeast enzymes involved in the steps of polyamine biosynthesis and adenosylmethionine biosynthesis. These are being used to obtain high yields of the enzymes to permit more complete study of the proteins and cofactors involved.